US experts disagree on whether Iran violated nuclear deal with powers

VIENNA, Nov 8 (Reuters) - A U.S. think-tank said Iran may
have violated last year's interim nuclear deal with world powers
by stepping up efforts to develop a machine that could enrich
uranium faster, but other experts said they saw no breach.

Iran's development of advanced enrichment centrifuges is
sensitive because, if successful, it could enable the country to
produce potential nuclear bomb material at a rate several times
that of the decades-old model now in use.

Western officials were not immediately available to comment
on the allegation by the Washington-based Institute for Science
and International Security (ISIS), which closely tracks Iran's
nuclear programme. There was no immediate comment from Tehran.

ISIS, whose founder David Albright often briefs U.S.
lawmakers and others on nuclear proliferation issues, cited a
finding in a new report by the International Atomic Energy
Agency (IAEA) about Iran.

The confidential document, issued to IAEA member states on
Friday, said that since the U.N. agency's previous report in
September Iran had "intermittently" been feeding natural uranium
gas into a single so-called IR-5 centrifuge at a research
facility.

The IR-5 is one of several new models that Iran has been
seeking to develop to replace the erratic, 1970s vintage IR-1
centrifuge that it now uses to produce refined uranium.

Unlike other advanced models under development -- IR-2m,
IR-4 and IR-6 -- at a research site at its Natanz enrichment
plant, Iran had until now not fed the IR-5 with uranium gas.

"Iran may have violated (the interim accord) by starting to
feed (natural uranium gas) into one of its advanced centrifuges,
namely the IR-5 centrifuge," ISIS said in an analysis.

But the Washington-based Arms Control Association, a
research and advocacy group, said it saw no violation, adding
that "no enriched uranium is being withdrawn from the machine".

Jofi Joseph, a former director for non-proliferation on the
White House National Security Council staff, also said Iran had
not violated the agreement. "That would only occur if Iran
introduced a brand new centrifuge model to the facility and
began feeding it uranium," he wrote in an email.

Iran says it produces low-enriched uranium to make fuel for
nuclear power plants. But if processed much further, refined
uranium could be turned into the explosive core of a bomb, which
the West fears may be the country's latent goal.

Tehran denies looking to build nuclear weapons.

Under last year's deal with the United States, Russia,
China, France, Germany and Britain, Iran can continue its
"current enrichment R&D (research and development) practices",
language that implies it should not expand them. The text of the
publicly released agreement did not elaborate on this point,
potentially leaving it open for interpretation.

It was one of the thorniest issues to resolve in the
negotiations on the temporary accord, which was designed to buy
time for talks on a permanent settlement by a Nov. 24 deadline.
It is expected to be a key issue also in any long-term deal.
(Reporting by Fredrik Dahl; Editing by Mark Heinrich and
Dominic Evans)